Yuhua MP Grace Fu, who is Culture, Community and Youth Minister, South West District Mayor Low Yen Ling and former PAP chairman Lim Boon Heng were also there.

SDP's Chee Soon Juan, 53, was accompanied by his wife Huang Chih-Mei, sister Chee Siok Chin and party supporters, and handed out cards and his party newsletter New Democrat.

He was overheard telling residents that the by-election could be held in a few weeks' time.

The vacant seat for Bukit Batok was triggered by the sudden resignation of former MP David Ong last month over an alleged extramarital affair with a PAP member in his branch, who has also resigned from the party.

Last week, the Elections Department said it would update the electoral registers on April 14, in a sign that the by-election could be called later this month.

Yesterday, both the PAP and SDP focused their outreach around the Yong Xing Coffee Shop that made headlines in June last year when it was sold for a record $31 million.

Mr Murali told reporters that he will focus on several areas if elected.

One is employment help. "We have government support like the Social Service Office and e2i, but beyond that, we can galvanise community support as well," he said.

He will also push for the Home Improvement Programme (HIP) for residents, adding: "There are a number of Bukit Batok flats that have not benefited from HIP yet."

Seniors who live alone can also get panic buttons in their flats. Mr Murali said he started a panic button installation fund at Paya Lebar and hopes to start a similar fund for Bukit Batok.

Paya Lebar is part of Aljunied GRC where he contested in last year's general election.

Dr Chee said his top priority, if elected, is to take care of residents and the estate. "I will be doing this on a full-time basis. They will have my undivided attention."

Besides local issues, he said he will also speak up in Parliament on national issues such as poverty, income gap, cost of living and prices of HDB flats and social mobility.